Phenomenological Phase—Parameter Fits to $N-N$ Data at Intermediate Energies

New $p-p$ and $n-p$ phase-parameter multiple energy fits (Y-IV) intended for the energy range from ∼8 MeV to ∼340 MeV employing 947 measurements for $p-p$ and 1023 for $n-p$ are discussed. Improvements over older work include: (a) more careful joining to low-energy data involving phase searches beginning at 1.397 MeV for $p-p$ and 3.205 MeV for $n-p$; (b) inclusion of triple scattering and polarization data at 430 MeV; (c) data lumping in smaller groups than previously; (d) increased accuracy of one-pion-exchange (OPE) phases; (e) graded introduction of OPE treatment. Related matters include: (1) effects of Coulomb field corrections and of corrections for the apparent violation of shortrange charge independence for the new fits and the older YRB1 (${\mathrm{K}}_0$) - YLAN4M; (2) effects of varying the difference between the $p-p$ and $n-p$ effective ranges within its uncertainty limits; (3) analyses of mockups of experiments designed to improve knowledge of the difference just mentioned; (4) comparisons of values of the pion-nucleon coupling constant ${g_0}^2$ derived from $p-p$ and $n-p$ data in relation to the long-range charge independence of $N-N$ interactions.